1. Field of the Invention
The present invention relates to a portable power pack, and more particularly, to a small portable power pack, which can be easily carried and used without the restriction of spaces and sites, and includes a fuel/air supply, which is connected to a fuel tank containing dimethyl ether (DME) fuel, and an engine, which performs a series of procedures, such as ignition, explosion, compression and exhaustion to convert mechanical energy to electric energy using the fuel delivered from the fuel/air supply thereby powering various devices, such as portable electronic devices and autonomous robots.
2. Description of the Related Art
As well known to those skilled in the art, electronic devices have been miniaturized due to the manufacturing technologies of Micro Electro-Mechanical Systems (MEMS), each of which has held the spotlight as one of the advanced technologies in 21st century. This technology has enabled the rapid development of portable electronic devices, such as a mobile phone, a Personal Data Assistant (PDA) and a notebook computer, and created new fields, such as a Micro-Air Vehicle (MAV) and a micro-robot, thereby providing driving force for realizing the ubiquitous age. However, a capacitor battery or a power pack (i.e., a portable power supply) having high power output is essentially required because a portable mobile communication device needs a greater amount of electric energy due to the increase of the display size thereof and the addition of picture and dynamic image functions and a micro-robot should be able to move in a wide range and operate in a long period of time.
At present, a lithium (Li) ion capacitor battery, which is mainly used in small electronic devices, has an energy density of about 90 W-h/kg. This battery can consecutively operate for 3 to 4 hours, and has to be recharged after that. Accordingly, in order to prepare for more developed ubiquitous age, there is essentially required a power pack having an energy density of 500 W-h/kg or more, which enables such electronic devices to operate in a longer period of time.
However, the existing power pack is too complicated to reduce its size. Even if the power pack is miniaturized, the capacity thereof is insufficient to block the multiple use.